Estabilidad de taludes

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  • Publicado : 6 de julio de 2010
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| | |[pic]Next | |Introduction
TSLOPE is used for analyses of circular or non-circular slip surfaces in which the user specifies the potential slip surface and the soil properties along that slip surface. Multiple slip surfaces can be analyzed for a site, the user can test the sensitivity of the results to small shifts in the slip surface and/or the specified soil properties and pore pressuresand thus conduct an intelligent search for the critical non-circular slip surface.
The program will search for the critical seismic coefficient, that is the seismic coefficient which reduces the factor of safety to unity.
TSLOPE offers a choice of methods for computing the factor of safety, either Spencer's Method or Morgenstern and Price's Method. Both methods fully satisfy equilibriumconditions. As will be discussed subsequently, there is a marginal increase in accuracy with increasing sophistication as one goes from Spencer to Morgenstern and Price.
The Simplified Bishop Method can be extended to non-circular slip surfaces and is then equivalent to Janbu's Simplified Method but for non-circular slip surfaces there tends to be a greater difference between the results obtained usingthese methods and methods which fully satisfy equilibrium. Academic studies (e.g. Boutrup et al, 1979; Frodlund et al, 1981) have usually indicated that use of the Simplified Janbu method gives factors of safety 10 or 15 % lower than methods which fully satisfy equilibrium unless a correction factor is applied, but greater differences have been reported in some practical applications. Boutrup etal. (1979) also found that the program STABL2, which uses the Simplified Janbu Method, "may give nonconservative and erroneous results for failure surfaces that intersect the top of the slope at steep angles, and where the strength is defined mainly in terms of the cohesion intercept."
Thus, in TSLOPE, which is primarily intended to be used for the analysis of non-circular slip surfaces, we onlyoffer use of Spencer's Method or the Morgenstern and Price Method, both of which fully satisfy equilibrium. As used in TSLOPE these methods are identical except that for Morgenstern and Price's method the user must specify the relative slopes of the inter-slice forces. Since the user does not normally know how to specify the distribution of the relative slopes of the inter-slice forces, it makesmore sense to use Spencer's Method. However, the Morgenstern and Price method should be used when Spencer's Method fails to converge or when Spencer's Method yields an unreasonable line of thrust.
TSLOPE may be used to analyze two-dimensional wedge-type failures in which case the sliding mass is divided into a number of vertical slices rather than the two or three wedges that may be used in handcomputations. The obtuse angle at the base of the wedge may, however, have to be rounded off when using TSLOPE in order to obtain convergence of the solution.
This program, like all computer programs, is no smarter than the engineer who uses it. We have tried to make the program reasonably simple to use and to provide clear instructions. However, if you have not previously attempted analyses of thekind performed by the program, you should probably seek advice from someone who has experience with this kind of analysis. You will not obtain the correct answer to the problem you are studying unless the field conditions are adequately represented. Even then you should not assume that you have computed the correct answer. The purpose of analyses such as are conducted with this program should beto obtain insight into an engineering problem, not to obtain numerical values which are taken at face value. For this reason, we have built various options into the program so that you can explore the effects of varying the assumptions made in modeling your problem as well as the effects of varying material properties. However, we cannot guarantee that the program works for all analyses that you...
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